<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>

    let week=prompt('请输入星期几')
    switch(week){
      case '星期一':
       document.write('monday ');
       break
       case '星期二':
       document.write('tuesday');
       break
       case '星期三':
       document.write('wednesday ');
       break
       case '星期四':
       document.write('thursday ');
       break
       case '星期五':
       document.write('friday');
       break
       case '星期六':
       document.write('saturday');
       break
       case '星期天':
       document.write('sunday');
       break
       default:

    }

  </script>
</body>
</html>